Surgically produced congenital diaphragmatic hernia in fetal rabbits.

Animal models of congenital diaphragmatic hernia (CDH) still are indispensable for the evolution of knowledge related to this disease and to fetal surgery in general. The lamb has provided the most reliable experimental design thus far. Considering the possible advantages of using rabbits (rather than lambs) namely lower costs, no need of special veterinary facilities, smaller body size, year-round availability, higher number of fetuses per pregnancy, and shorter gestational period, a successful model of CDH was developed in fetal rabbits. Sixteen pregnant New Zealand rabbits underwent hysterotomy and fetal operation. Group 1 (6 does) underwent surgery on gestational day 20 and group 2 (10 does) on gestational day 24 or 25. The normal full gestation time is 31 to 33 days. In group 1, the CDH was created by transabdominal puncture and dilatation of the fetal diaphragm. In group 2, the CDH was created through open thoracotomy, either left or right. The fetuses were delivered by cesarean section on gestational day 30. The overall fetal survival rate was 0 for group 1 and 70% for group 2. All operated fetuses in group 2 that were born alive had CDH. The histological morphometric examinations (radial alveolar count after sustained lung expansion) of the normal and operated fetuses in group 2 showed pulmonary hypoplasia in all the lungs on the same side as the CDH (statistical analysis was performed using the Neuman-Keuls test and analysis of variance; the significance level was set at .05).(ABSTRACT TRUNCATED AT 250 WORDS)